Process and catalyst for producing styrenic polymer

ABSTRACT

There is disclosed a process for producing a styrenic polymer which comprises polymerizing at least one styrenic monomer by the use of a polymerization catalyst comprising in combination (A) at least one transition metal compounds, (B) an aluminoxane, (C) a coordination complex compound comprising a cation and an anion in which a plurality of radicals are bonded to a metal and (D) an organoaluminum compound. The above process is capable of producing a styrenic polymer which has high degree of syndiotactic configuration and a wide range of molecular weight distribution and is minimized in residual metallic components at a low production cast with a high efficiency.

This is a Continuation of application Ser. No. 08/612,077 filed on Mar.7, 1996, U.S. Pat. No. 5,786,403, which is a continuation of Ser. No.08/131,616 filed Oct. 5, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved process for producing astyrenic polymer. More particularly it pertains to a process forproducing a styrenic polymer which has high degree of syndiotacticconfiguration and a wide range of molecular weight distribution and isreduced in residual metallic components at a low production cost with ahigh efficiency.

2. Description of Related Art

There have heretofore been known the processes for producinghigh-performance styrenic polymer having high degree of syndiotacticconfiguration in high yield by allowing a reaction product of analuminoxane with a transition metal complex to act on styrene. (Refer toJapanese Patent Application Laid-Open Nos. 187708/1987, 179906/1988,241009/1988, etc.). However, the styrenic polymer produced by any of theabove-disclosed processes involves the problem of moldability due to theusually narrow range of molecular weight distribution. Accordingly thereis desired a styrenic polymer which has high degree of syndiotacticconfiguration and besides a wide range of molecular weight distribution.

In order to produce such a styrenic polymer having a wide range ofmolecular weight distribution, there has heretofore been employed amethod in which a high molecular styrenic polymer and a low molecularstyrenic polymer are mixed with each other by melt kneading or the liketo expand the range of molecular weight distribution. However, theaforesaid method involves the problem of requiring much labor and effortfor uniform mixing.

There is also known a method of expanding the molecular weightdistribution by the use of a plurality of transition metal compounds andan aluminoxane. (Refer to Japanese Patent Application Laid-Open No.119006/1991). Nevertheless the above-mentioned method suffers thedisadvantage that a large requirement of an aluminoxane increases thecatalyst cost and the amount of residual metallic components isexcessive making it unserviceable unless deashing is put into practice.

Under such circumstances it is an object of the present invention toprovide a process for producing a styrenic polymer which has high degreeof syndiotactic configuration and a wide range of molecular weightdistribution and is reduced in residual metallic components at a lowproduction cost with a high efficiency.

SUMMARY OF THE INVENTION

As the result of intensive research and investigation accumulated by thepresent inventors in order to attain the above-mentioned object, it hasbeen found, in the combined polymerization catalyst comprising atransition metal compound, an aluminoxane, a specific ion complex and anorganoaluminum compound, that the incorporation of said organoaluminumcompound causes the polymer portion produced by the aluminoxane to shiftto the side of the lower molecular weight but does not cause the polymerportion produced by the ion complex to shift to said side and thereforethe combined use of the aluminoxane, the ion complex and theorganoaluminum compound can expand the range of molecular weightdistribution; the combined use of the aluminoxane and the ion complexcan reduce the requirement of the expensive aluminoxane as compared withthe conventional methods; the use of a plurality of transition metalcompounds can set the molecular weight distribution at a desired valuethereby enabling the range of said distribution to be expanded; andafter all the use of said polymerization catalyst can attain the objectof the present invention. The present invention has been accomplished onthe basis of the above-mentioned finding and information.

Specifically the present invention provides a process for producing astyrenic polymer which comprises polymerizing at least one styrenicmonomer by the use of a polymerization catalyst comprising incombination (A) a transition metal compound, (B) an aluminoxane, (C) acoordination complex compound comprising a cation and an anion in whicha plurality of radicals are bonded to a metal and (D) an organoaluminumcompound, and at the same time, a process for producing a styrenicpolymer which comprises polymerizing at least one styrenic monomer bythe use of a polymerization catalyst comprising in combination (A) aplurality of transition metal compounds and the aforesaid components (B)an aluminoxane, (C) a coordination complex compound comprising a cationand an anion in which a plurality of radicals are bonded to a metal and(D) an organoaluminum compound.

DESCRIPTION OF PREFERRED EMBODIMENT

In the process according to the present invention, the combination ofthe components (A), (B), (C) and (D) is employed as the polymerizationcatalyst. Various transition metal compounds are available as thecomponent (A) and exemplified by a compound of a group 3 to 6 metal ofthe Periodic Table and a compound of lanthanum series metal, of which ispreferable a compound of a group 4 metal (titanium, zirconium, hafnium,vanadium, etc.). Various titanium compounds can be used and a preferredexample is at least one compound selected from the group consisting oftitanium compounds and titanium chelate compounds represented by thegeneral formula:

    TiR.sup.1.sub.a R.sup.2.sub.b R.sup.3.sub.c R.sup.4.sub.4-(a+b+c)(I)

or

    TiR.sup.1.sub.d R.sup.2.sub.e R.sup.3.sub.3-(d+e)          (II)

wherein R¹, R², R³ and R⁴ are each a hydrogen atom, an alkyl grouphaving 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbonatoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, anarylalkyl group, an acyloxy group having 1 to 20 carbon atoms, acyclopentadienyl group, a substituted cyclopentadienyl group, an indenylgroup or a halogen atom; a, b and c are each an integer from 0 to 4; andd and e are each an integer from 0 to 3.

R¹, R², R³ and R⁴ in the general formulae (I) and (II) each represent ahydrogen atom, an alkyl group having 1 to 20 carbon atoms (specifically,methyl group, ethyl group, propyl group, butyl group, amyl group,isoamyl group, isobutyl group, octyl group and 2-ethylhexyl group), analkoxy group having 1 to 20 carbon atoms (specifically, methoxy group,ethoxy group, propoxy group, butoxy group, amyloxy group, hexyloxygroup, and 2-ethylhexyloxy group), an aryl group having 6 to 20 carbonatoms, an alkylaryl group, an arylalkyl group (specifically, phenylgroup, tolyl group, xylyl group and benzyl group), an acyloxy grouphaving 1 to 20 carbon atoms (specifically, heptadecylcarbonyloxy group),a cyclopentadienyl group, a substituted cyclopentadienyl group(specifically, methylcyclopentadienyl group,1,2-dimethylcyclopentadienyl group and pentamethylcyclopentadienylgroup), an indenyl group or a halogen atom (specifically, chlorine,bromine, iodine and fluorine). These R¹, R², R³, R⁴ may be the same asor different from each other. Furthermore, a, b and c are each aninteger from 0 to 4, and d and e are each an integer from 0 to 3.

More desirable titanium compounds include a titanium compoundrepresented by the formula:

    TiRXYZ                                                     (III)

wherein R represents a cyclopentadienyl group, a substitutedcyclopentadienyl group or an indenyl group;

X, Y, and Z, independently of one another, are a hydrogen atom, an alkylgroup having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbonatoms, an aryl group having 6 to 20 carbon atoms, an aryloxy grouphaving 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbonatoms or a halogen atom.

The substituted cyclopentadienyl group represented by R in the aboveformula is, for example, a cyclopentadienyl group substituted by atleast one of an alkyl group having 1 to 6 carbon atoms, morespecifically, methylcyclopentadienyl group, 1,3-dimethylcyclopentadienylgroup, 1,2,4-trimethylcyclopentadienyl group,1,2,3,4-tetramethylcyclopentadienyl group, pentamethylcyclopentadienylgroup or the like. In addition, X, Y, and Z are each independently ahydrogen atom, an alkyl group having 1 to 12 carbon atoms (specifically,methyl group, ethyl group, propyl group, n-butyl group, isobutyl group,amyl group, isoamyl group, octyl group and 2-ethylhexyl group), analkoxy group having 1 to 12 carbon atoms (specifically, methoxy group,ethoxy group, propoxy group, butoxy group, amyloxy group, hexyloxygroup, octyloxy group and 2-ethylhexyl group), an aryl group having 6 to20 carbon atoms (specifically, phenyl group and naphthyl group), anaryloxy group having 6 to 20 carbon atoms (specifically, phenoxy group),an arylalkyl group having 6 to 20 carbon atoms (specifically, benzylgroup) or a halogen atom (specifically, chlorine, bromine, iodine andfluorine).

Specific examples of the titanium compound represented by the generalformula (III) include

cyclopentadienyltrimethyltitanium,

cyclopentadienyltriethyltitanium,

cyclopentadienyltripropyltitanium,

cyclopentadienyltributyltitanium,

cyclopentadienyltrichlorotitanium,

methylcyclopentadienyltrimethyltitanium,

1,3-dimethylcyclopentadienyltrimethyltitanium,

pentamethylcyclopentadienyltrimethyltitanium,

pentamethylcyclopentadienyltriethyltitanium,

pentamethylcyclopentadienyltripropyltitanium,

pentamethylcyclopentadienyltributyltitanium,

pentamethylcyclopentadienyltrichlorotitanium,

cyclopentadienylmethyltitanium dichloride,

cyclopentadienylethyltitanium dichloride,

pentamethylcyclopentadienylmethyltitanium dichloride,

pentamethylcyclopentadienylethyltitanium dichloride,

cyclopentadienyldimethyltitanium monochloride,

cyclopentadienyldiethyltitanium monochloride,

cyclopentadienyltitanium trimethoxide,

cyclopentadienyltitanium triethoxide,

cyclopentadienyltitanium tripropoxide,

cyclopentadienyltitanium triphenoxide,

pentamethylcyclopentadienyltitanium trimethoxide,

pentamethylcyclopentadienyltitanium triethoxide,

pentamethylcyclopentadienyltitanium tripropoxide,

pentamethylcyclopentadienyltitanium tributoxide,

pentamethylcyclopentadienyltitanium triphenoxide,

cyclopentadienyltitanium trichloride,

pentamethylcycloentadienyltitanium trichloride,

cyclopentadienylmethoxyltitanium dichloride,

cyclopentadienyldimethoxytitanium chloride,

pentamethylcyclopentadienylmethoxytitanium dichloride,

cyclopentadienyltribenzyltitanium,

pentamethylcyclopentadienylmethyldiethoxytitanium,

indenyltitanium trichloride, indenyltitanium trimethoxide,

indenyltitanium triethoxide, indenyltrimethyltitanium and

indenyltribenzyltitanium.

Of these titanium compounds, a compound not containing a halogen atom ispreferred and a titanium compound having one πelectron type ligand isparticularly desirable.

Furthermore, a condensed titanium compound represented by the generalformula may be used as the titanium compound. ##STR1## wherein R⁵ and R⁶each represent a halogen atom, an alkoxy group having 1 to 20 carbonatoms or an acyloxy group; and k is an integer from 2 to 20.

Furthermore, the above titanium compounds may be used in the form of acomplex formed with an ester, an ether or a phosphine.

The trivalent titanium compound represented by the formula (IV)typically includes a trihalogenated titanium such as titaniumtrichloride; and a cyclopentadienyltitanium compound such ascyclopentadienyltitanium dichloride, and also those obtained by reducinga tetravalent titanium compound. These trivalent titanium compounds maybe used in the form of a complex formed with an ester, an ether or aphosphine.

In addition, examples of the zirconium compound used as the transitionmetal compound include tetrabenzylzirconium, zirconium tetraethoxide,zirconium tetrabutoxide, bisindenylzirconium dichloride,triisopropoxyzirconium chloride, zirconium benzyl dichloride andtributoxyzirconium chloride. Examples of the hafnium compound includetetrabenzylhafnium, hafnium tetraethoxide and hafnium tetrabutoxide.Examples of the vanadium compound include vanadyl bisacetylacetonato,vanadyl triacetylacetonato, vanadyl triethoxide and vanadyltripropoxide. Of these transition metal compounds, the titaniumcompounds are particularly suitable.

Aside from the foregoing, the transition metal compounds constitutingthe component (A) of the catalyst include the transition metal compoundwith two ligands having conjugated π electrons, for example, at leastrepresented by the general formula:

    MR.sup.7 R.sup.8 R.sup.9 R.sup.10                          (V)

wherein M is titanium, zirconium or hafnium; R⁷ and R⁸ are each acyclopentadienyl group, substituted cyclopentadienyl group, indenylgroup or fluorenyl group; and R⁹ and R¹⁰ are each a hydrogen atom, ahalogen atom, hydrocarbon radical having 1 to 20 carbon atoms, alkoxygroup having 1 to 20 carbon atoms, amino group or thioalkoxyl grouphaving 1 to 20 carbon atoms, but R⁷ and R⁸ may be each crosslinked by ahydrocarbon radical having 1 to 5 carbon atoms, alkylsilyl group having1 to 20 carbon atoms and 1 to 5 silicon atoms or germanium-containinghydrocarbon group having 1 to 20 carbon atoms and 1 to 5 germaniumatoms.

In more detail, each of R⁷ and R⁸ in the general formula (V) designatesa cyclopentadienyl group, substituted cyclopentadienyl group, morespecifically,

methylcyclopentadienyl group;

1,3-dimethylcyclopentadienyl group;

1,2,4-trimethylcyclopentadienyl group;

1,2,3,4-tetramethylcyclopentadienyl group;

pentamethylcyclopentadienyl group;

trimethylsilylcyclopentadienyl group;

1,3-di(trimethylsilyl)cyclopentadienyl group;

1,2,4-tri(trimethylsilyl)cyclopentadienyl group;

tert-butylcyclopentadienyl group;

1,3-di(tert-butyl)cyclopentadienyl group;

1,2,4-tri(tert-butyl)cyclopentadienyl group or the like,

indenyl group, substituted indenyl group, more specifically,methylindenyl group; dimethylindenyl group; trimethylindenyl group orthe like, fluorenyl group, or substituted fluorenyl group such asmethylfluorenyl group, and may be the same or different and crosslinkedby a alkylidene group having 1 to 5 carbon atoms, more specifically,methine group; ethylidene group; propylidene group; dimethylcarbyl.groupor the like, or an alkylsilyl group having 1 to 20 carbon atoms and 1 to5 silicon atoms, more specifically, dimethylsilyl group; diethylsilylgroup; dibenzylsilyl group or the like. Each of R⁹ and R¹⁰ independentlyindicates, as described above but more specifically, a hydrogen atom; analkyl group having 1 to 20 carbon atoms such as methyl group, ethylgroup, propyl group, n-butyl group, isobutyl group, amyl group, isoamylgroup, octyl group or 2-ethylhexyl group; an aryl group having 6 to 20carbon atoms such as phenyl group or naphthyl group; an arylalkyl grouphaving 7 to 20 carbon atoms such as benzyl group; an alkoxyl grouphaving 1 to 20 carbon atoms such as methoxyl group, ethoxyl group,propoxyl group, butoxyl group, amyloxyl group, hexyloxyl group,octyloxyl group or 2-ethylhexyloxyl group; an aryloxyl group having 6 to20 carbon atoms such as phenoxyl group; an amino group; or a thioalkoxylgroup having 1 to 20 carbon atoms.

Specific examples of the transition metal compounds represented by thegeneral formula (V) include

bis(cyclopentadienyl)dimethyltitanium;

bis(cyclopentadienyl)diethyltitanium;

bis(cyclopentadienyl)dipropyltitanium;

bis(cyclopentadienyl)dibutyltitanium;

bis(methylcyclopentadienyl)dimethyltitanium;

bis(tert-butylcyclopentadienyl)dimethyltitanium;

bis(1,3-dimethylcyclopentadienyl)dimethyltitanium;

bis(1,3-di-tert-butylcyclopentadienyl)dimethyltitanium;

bis(1,2,4-trimethylcyclopentadienyl)dimethyltitanium;

bis(1,2,3,4-tetramethylcyclopentadienyl)dimethyltitanium;

bis(pentamethylcyclopentadiemyl)dimethyltitanium;

bis(trimethylsilylcyclopentadienyl)dimethyltitanium;

bis(1,3-di(trimethylsilyl)cyclopentadienyl)dimethyltitanium;

bis(1,2,4-tri((trimethylsilyl)cyclopentadienyl)

dimethyltitanium; bis(indenyl)dimethyltitanium;

bis(fluorenyl)dimethyltitanium;

methylenebis(cyclopentadienyl)dimethyltitanium;

ethylidenebis(cyclopentadienyl)dimethyltitanium;

methylenebis(2,3,4,5-tetramethylcyclopentadienyl)dimethyltitanium;

ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)dimethyltitanium;

dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)dimethyltitanium;

methylenebisindenyldimethyltitanium;

ethylidenebisindenyldimethyltitanium;

dimethylsilylbisindenyldimethyltitanium;

methylenebisfluorenyldimethyltitanium;

ethylidenbisfluorenyldimethyltitanium;

dimethylsilylbisfluorenyldimethyltitanium;methylene(tertbutylcyclopentadienyl)(cyclopentadienyl)dimethyltitanium;

methylene(cyclopentadienyl)(indenyl)dimethyltitanium;

ethylidene(cyclopentadienyl)(indenyl)dimethyltitanium;

dimethylsilyl(cyclopentadienyl)(indenyl)dimethyltitanium;

methylene(cyclopentadienyl)(fluorenyl)dimethyltitanium;

ethylidene(cyclopentadienyl)(fluorenyl)dimethyltitanium;

dimethylsilyl(cyclopentadienyl)(fluorenyl)dimethyltitanium;

methylene(indenyl)(fluorenyl)dimethyltitanium;

ethylidene(indenyl)(fluorenyl)dimethyltitanium;

dimethylsilyl(indenyl)(fluorenyl)dimethyltitanium;

bis(cyclopentadienyl)dibenzyltitanium;

bis(tert-butylcyclopentadienyl)dibenzyltitanium;

bis( methylcyclopentadienyl)dibenzyltitanium;

bis( 1,3-dimethylcyclopentadienyl)dibenzyltitaniu;

bis(1,2,4-trimethylcyclopentadienyl)dibenzyltitanium;

bis(1,2,3,4-tetramethylcyclopentadienyl)dibenzyltitanium;

bis( pentamethylcyclopentadienyl)dibenzyltitanium;

bis(trimethylsilylcyclopentadienyl)dibenzyltitanium;

bis 1,3-di-(trimethylsilyl)cyclopentadienyl!dibenzyltitanium;

bis 1,2,4-tri(trimethylsilyl)cyclopentadienyl!dibenzyltitanium;

bis( indenyl )dibenzyltitanium;

bis(fluorenyl)dibenzyltitanium;

methylenebis(cyclopentadienyl)dibenzyltitanium;

ethylidenebis(cyclopentadienyl)dibenzyltitanium;

methylenebis(2,3,4,5-tetramethylcyclopentadienyl)dibenzyltitanium;

ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)dibenzyltitanium;

dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)dibenzyltitanium;

methylenebis(indenyl)dibenzyltitanium;

ethylidenebis(indenyl)dibenzyltitanium;

dimethylsilylbis(indenyl)dibenzyltitanium;

methylenebis(fluorenyl)dibenzyltitanium;

ethylidenebis(fluorenyl)dibenzyltitanium;

dimethylsilylbis(fluorenyl)dibenzyltitanium;

methylene(cyclopentadienyl)(indenyl)dibenzyltitanium;

ethylidene(cyclopentadienyl)(indenyl)dibenzyltitanium;

dimethylsilyl(cyclopentadienyl)(indenyl)dibenzyltitanium;

methylene(cyclopentadienyl)(fluorenyl)dibenzyltitanium;

ethylidene(cyclopentadienyl)(fluorenyl)dibenzyltitanium;

dimethylsilyl(cyclopentadienyl)(fluorenyl)dibenzyltitanium;

methylene(indenyl)(fluorenyl)dibenzyltitanium;

ethylidene(indenyl)(fluorenyl)dibenzyltitanium;

dimethylsilyl(indenyl)(fluorenyl)dibenzyltitanium;

biscyclopentadienyltitanium dimethoxide;

biscyclopentadienyltitanium diethoxide;

biscyclopentadienyltitanium dipropoxide;

biscyclopentadienyltitanium dibutoxide;

biscyclopentadienyltitanium dipheoxide;

bis(methylcyclopentadienyl)titanium dimethoxide;

bis(1,3-dimethylcyclopentadienyl)titanium dimethoxide;

bis(1,2,4-trimethylcyclopentadienyl)titanium dimethoxide;

bis(1,2,3,4-tetramethylcyclopentadienyl)titanium dimethoxide;

bispentamethylcyclopentadienyltitanium dimethoxide;

bis(trimethylsilylcyclopentadienyl)titanium dimethoxide;

bis 1,3-di(trimethylsilyl)cyclopentadienyl!titanium dimethoxide;

bis 1,2,4-tri(trimethylsilyl)cyclopentadienyl!titanium dimethoxide;

bisindenyltitanium dimethoxide;

bisfluorenyltitanium dimethoxide;

methylenebiscyclopentadienyltitanium dimethoxide;

ethylidenebiscyclopentadienyltitanium dimethoxide;

methylenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide;

ethylidenebis(2,3,4,5-tetramethylcyclopentadienyl)titanium dimethoxide;

dimethylsilylbis(2,3,4,5-tetramethylcyclopentadienyl)titaniumdimethoxide;

methylenebisindenyltitanium dimethoxide;

methylenebis(methylindenyl)titanium dimethoxide;

ethylidenebisindenyltitanium dimethoxide;

dimethylsilylbisindenyltitanium dimethoxide;

methylenebisfluorenyltitanium dimethoxide;

methylenebis (methyl fluorenyl )titanium dimethoxide;

ethylidenebisfluorenyltitanium dimethoxide;

dimethylsilylbisfluorenyltitanium dimethoxide;

methylene(cyclopentadienyl)(indenyl)titanium dimethoxide;

ethylidene(cyclopentadienyl)(indenyl)titanium dimethoxide;

dimethylsilyl(cyclopentadienyl)(indenyl)titanium dimethoxide;

methylene(cyclopentadienyl)(fluorenyl)titanium dimethoxide;

ethylidene(cyclopentadienyl)(fluorenyl)titanium dimethoxide;

dimethylsilyl(cyclopentadienyl)(fluorenyl)titanium dimethoxide;

methylene(indenyl)(fluorenyl)titanium dimethoxide;

ethylidene(indenyl)(fluorenyl)titaniumim dimethoxide;

dimethylsilyl(indenyl)(fluorenyl)titanium dimethoxide,

isopropylidene(cyclopentadienyl)(fluorenyl)titanium dichloride, and

isopropylidene(cyclopentadienyl)(fluorenyl)titanium dimethoxide.

Examples of the transition metal compounds represented by the formula(V) wherein M is zirconium includeethylidenebiscyclopentadienylzirconium dichloride,ehylidenbiscyclopentadienylzirconium dimethoxide,dimethylsilylbiscyclopentadienylzirconium dimethoxide,isopropylidene(cyclopentadienyl)(fluorenyl)zirconium dichloride, etc.Examples of the hafnium compounds according to the general formula (V)include ethylidenebiscyclopentadienylhafnium dimethoxide,dimethylsilylbiscyclopentadienylhafnium dimethoxide, etc. Particularlydesirable transition metal compounds among them are titanium compounds.

The transition metal compound as the component (A) of the catalystaccording to the present invention may be used alone or in combinationwith at least one of them. In the case of the combined use, it ispreferable that the transition metal compounds be properly selected onthe basis of the chemical shift in ¹³ C-NMR of the carbon in the methoxygroup as the index when at least one u-bonded ligand in the transitionmetal compound is methoxized. Since the weight-average molecular weightof the styrenic polymer to be produced decreases with increase in thechemical shift value of the ¹³ C-NMR, it is possible to set the range ofthe molecular weight distribution of the styrenic polymer to the desiredvalue by properly selecting a plurality of transition metal compoundseach having a different chemical shift value from one another.

The aluminoxane which is the component (B) of the polymerizationcatalyst is a compound obtained by bringing an organoaluminum compoundinto contact with a condensation agent, and includes a chain aluminoxanerepresented by the general formula (VI): ##STR2## wherein R¹¹ is analkyl group having 1 to 20 carbon atoms, is preferably a methyl groupand p is a number from 0 to 50, preferably 5 to 30; and a cyclicaluminoxane represented by the general formula (VII): ##STR3## WhereinR¹¹ is as previously defined and q is a number from 2 to 50, preferably5 to 30.

The organoaluminum compound is exemplified by a trialkylaluminum such astrimethylaluminum, triethylaluminum and triisobutylaluminum, of which ispreferable trimethylaluminum.

The condensation agent is typified by water and exemplified by anarbitrary substance which undergoes condensation reaction with atrialkylaluminum such as copper sulphate pentahydrate, water adsorbed inan inorganic or organic substance and so forth.

In general, the contact product of an organoaluminum compounds such astrialkylaluminum and water contains the above-mentioned chainalkylaluminoxane and cyclic alkylaluminoxane together with unreactedtrialkylaluminum, various mixture of condensates and further themolecules resulting from association in an intricate manner thereof.Accordingly, the resultant contact product varies widely depending uponthe conditions of contact of trialkylaluminum with water as thecondensation agent.

The reaction of the alkylaluminum compound and water is not specificallylimited in the above case but may be effected according to the publiclyknown methods, which are exemplified by (1) a method in which anorganoaluminum compound is dissolved in an organic solvent an thenbrought into contact with water, (2) a method in which an organoaluminumcompound is first added to the reaction system at the time ofpolymerization and thereafter water is added thereto, and (3) a methodin which an organoaluminum compound is reacted with the water ofcrystallization contained in metal salts and the like, or the wateradsorbed in inorganic or organic materials. The above-mentioned watermay contain up to about 20% of ammonia, amine such as ethylamine, sulfercompound such as hydrogen sulfide, phosphorus compound such asphosphate, or the like. The above-mentioned reaction proceeds even inthe absence of a solvent but is preferably carried out in a solvent.Examples of the suitable solvent to be used here include aliphatichydrocarbons such as hexane, heptane and decane, aromatic hydrocarbonssuch as benzene, toluene and xylene, and the like. The aluminoxane (e.g.an alkylaluminoxane) is preferably obtained by a method wherein thesolid residue produced after contact reaction in the case of awater-containing compound being used is removed by means of filtrationand the filtrate is heat treated under atmospheric or reduced pressureat 30 to 200° C., preferably 40 to 150° C. for 20 minutes to 8 hours,preferably 30 minutes to 5 hours while distilling away the solvent used.

The temperature in the aforementioned heat treatment may be pertientlydetermined according to the various conditions, but should be usuallywithin the above-described ranage. The temperature lower than 30° C.fails to bring about the prescribed effect, whereas that exceeding 200°C. causes thermal decomposition of aluminoxane itself, each resulting inunfavorable consequence.

The reaction product is obtained in the form of colorless solid orsolution depending upon the heat treatment conditions, and can be usedas the catalyst solution by dissolving in or diluting with a hydrocarbonsolvent according to the demand.

Suitable examples of the aluminoxane, that is, the contact product oforganoaluminum compound and a condensation agent which is used as thecomponent of the catalyst, especially an alkylaluminoxane are those inwhich the area of the high magnetic field component in the methyl protonsignal region due to the aluminum-methyl group (Al-CH₃) bond as observedby the proton nuclear magnetic resonance method is not more than 50% ofthe total signal area. That is, in a proton nuclear magnetic resonance(¹ H-NMR) spectral analysis of the alkylaluminoxane in toluene solventat room temperature, the methyl proton signal due to Al-CH₃ is observedin the region of 1.0 to -0.5 ppm (tetramethylsilane (TMS) standard).Since the proton signal of TMS (0 ppm) is in the region of the methylproton signal due to Al-CH₃, the methyl proton signal due to Al-CH₃ ismeasured with 2.35 ppm methyl proton signal of toluene in TMS standard.The methyl proton signal due to Al-CH₃ is divided into two comonents:the high magnetic field component in the -0.1 to -0.5 ppm region and theother magnetic field component in the 1.0 to -0.1 ppm region. Inalkylaluminoxane preferably used as component (B) of the catalyst in thepresent invention, the area of the high magnetic field component is notmore than 50%, preferably 45 to 5% of the total signal area in the 1.0to -0.5 ppm region.

As the coordination complex compound comprising a cation and an anion inwhich a plurality of radicals are bonded to a metal, that is, thecomponent (C) of the polymerization catalyst, there are preferablyusable the coordination complex compounds represented by the followinggeneral formula (VIII) or (IX):

    ( L.sup.1 -H!.sup.g+).sub.h ( M.sup.1 X.sup.1 X.sup.2 . . . X.sup.n !.sup.(n-m)-)i                                            (VIII)

or

    ( L.sup.2 !.sup.g+).sub.h ( M.sup.2 X.sup.1 X.sup.2 . . . X.sup.n !.sup.(n-m)-)i                                            (IX)

wherein L² is M³, R¹² R¹³ M⁴ or R¹⁴ ₃ C as hereinafter described; L₁ isa Lewis base; M¹ and M² are each a metal selected from Groups 5 to 15 ofthe Periodic Table; M³ is a metal selected from Groups 8 to 12 of thePeriodic Table; M⁴ is a metal selected from Groups 8 to 10 of thePeriodic Table; X¹ to X^(n) are each a hydrogen atom, dialkylaminogroup, alkoxy group, aryloxy group, alkyl group having 1 to 20 carbonatoms, aryl group having 6 to 20 carbon atoms, alkylaryl group,arylalkyl group, substituted alkyl group, organometalloid group orhalogen atom; R¹² and R¹³ are each a cyclopetnadienyl group, substitutedcyclopentadienyl group, indenyl group or fluorenyl group; R¹⁴ is analkyl group; m is the valency of each of M¹ and M², indicating aninteger of 1 to 7; n is an integer of 2 to 8; g is the ion valency ofeach of L¹ -H! and L² !, indicating an integer of 1 to 7; h is aninteger of 1 or more; and i=hxg/(n-m).

Specific examples of M¹ and M² include B, Al, Si, P, As, Sb, etc.; thoseof M³ include Ag, Cu, etc.; and those of M⁴ include Fe, Co, Ni, etc.Specific examples of X¹ to X^(n) include dialkylamino group such asdimethylamino and diethylamino; alkoxyl group such as methoxyl, ethoxyland n-butoxyl; aryloxyl group such as phenoxyl, 2,6-dimethylpheoxyl andnaphthyloxyl; alkyl group having 1 to 20 carbon atoms such as methyl,ethyl, n-propyl, iso-propyl, n-butyl, n-octyl and 2-ethylhexyl; arylgroup having 6 to 20 carbon atoms, alkylaryl group or arylalkyl groupsuch as phenyl, p-tolyl, benzyl, pentafluorophenyl,3,5-di(trifluoromethyl)phenyl, 4-tert-butylphenyl, 2,6-dimethylphenyl,3,5-dimethylphenyl, 2,4-dimethylphenyl and 1,2-dimethylphenyl; halogensuch as F, Cl, Br and I; and organometalloid such as pentamethylantimonygroup, trimethylsilyl group, trimethylgermyl group, diphenylarsinegroup, dicyclohexylantimony group and diphenylboron group. Specificexamples of substituted cyclopetnadienyl group of R¹² and R¹³ includemethylcyclopentadienyl, butylcyclopentadienyl andpentamethylcyclopentadienyl.

Among the compounds represented by the general formula (VIII) or (IX),specific examples of preferably usable compounds include, as thecompound of general formula (VIII), triethylammonium tetraphenylborate,tri(n-butyl)ammonium tetraphenylborate, trimethylammoniumtetraphenylborate, triethylammonium tetra(pentafluorophenyl)borate,tri(n-butyl)ammonium tetra(pentafluorophenyl)borate, triethylammoniumhexafluoroarsenate, etc., and as the compound of general formula (IX),pyridinium tetra(pentafluorophenyl)borate, pyrroliniumtetra(pentafluorophenyl)borate, N,N-dimethylaniliniumtetra(pentafluorophenyl)borate, methyldiphenylammoniumtetra(pentafluorophenyl)borate, ferrocenium tetraphenylborate,dimethylferrocenium tetra(pentafluorophenyl)borate, ferroceniumtetra(pentafluorophenyl)borate, decamethylferroceniumtetra(pentafluorophenyl)borate, acetylferroceniumtetra(pentafluorophenyl)borate, formylferroceniumtetra(pentafluorophenyl)borate, cyanoferroceniumtetra(pentafluorophenyl)borate, silver tetraphenylborate, silvertetra(pentafluorophenyl)borate, trityl tetraphenylborate, trityltetra(pentafluorophenyl)borate, silver hexafluoroarsenate, silverhexafluoroantimonate, silver tetrafluoroborate, etc.

On the other hand, various organometallic compounds are available as thecomponent (D) of the polymerization catalyst, and exemplified by thoserepresented by the general formula (X):

    R.sup.15.sub.r Al(OR.sup.16).sub.s H.sub.t Y.sup.1.sub.u   (X)

wherein R¹⁵ and R¹⁶ each independently represent an alkyl group having 1to 8 carbon atoms, preferably 1 to 4 carbon atoms; Y¹ represents ahalogen; r, s, t and u are 0<r≦3, 0≦s<3 and 0≦t<3, respectively, andr+s+t+u=3.

The activity of the catalyst is further improved by adding the abovecompound.

The organoaluminum compound represented by the above formula (X) can beexemplified as shown below. Those corresponding to t=u=o are representedby the formula: R¹⁵ _(r) Al(OR¹⁶)_(3-r) (wherein R¹⁵ and R¹⁶ are aspreviously defined and r is preferably a number of 1.5≦r≦3). Thosecorresponding to s=t=0 are represented by the formula: R¹⁵ AlY¹ _(3-r)(wherein R¹⁵ and Y¹ are as previously defined and r is preferably anumber of 0<r<3). Those corresponding to s=u=0 are represented by theformula: R¹⁵ _(r) AlH_(3-r) (wherein R¹⁵ is as previously defined and ris preferably a number of 2≦r<3). Those corresponding to t=0 arerepresented by the formula: R¹⁵ _(r) Al(OR¹⁶)_(s) Y¹ _(u) (wherein R¹⁵,R¹⁶ and Y¹ are as previously defined and 0<r≦3, 0≦s<3, 0≦u<3 andr+s+u=3.

In the organoaluminum compound represented by the formula (X), thecompound wherein t=u=0 and r=3 is selected from, for example,trialkylaluminum such as triethylaluminum and tributylaluminum, orcombination thereof, and those preferred are triethylaluminum,tri-n-butyl-aluminum and triisobutylaluminum. In the case of t=u=o and1.5≦r<3, included are dialkylaluminum alkoxide such as diethylaluminumethoxide and dibutylaluminum butoxide; alkylaluminum sesquialkoxide suchas ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide; aswell as partially alkoxylated alkylaluminum having an averagecomposition represented by R¹⁵ ₂.5 Al(OR¹⁶)₀.5. Examples of the compoundcorresponding to the case where s=t=0 include a partially halogenatedalkylaluminum including dialkylaluminum halogenide (r=2) such asdiethylaluminum chloride, dibutylaluminum chloride and diethylaluminumbromide; alkylaluminum sesquihalogenide (r=1.5) such as ethylaluminumsesquichloride, butylaluminum sesquichloride and ethylaluminumsesquibromide; and alkylaluminum dihalogenide (r=1) such asethylaluminum dichloride, propylaluminum dichloride and butylaluminumdibromide. Examples of the compound corresponding to the case in whichs=u=0 includes a partially hydrogenated alkylaluminum includingdialkylaluminum hydride (r=2) such as diethylaluminum hydride anddibutylaluminum hydride; alkylaluminum dihydride (r=1) such asethylaluminum dihydride and propylaluminum dihydride. Examples of thecompound corresponding to the case in which t=0 include a partiallyalkoxylated and halogenated alkylaluminum such as ethylaluminumethoxychloride, butylaluminumbutoxy chloride and ethylaluminumethoxy bromide(r=s=u=1).

The catalyst to be used in the process of the present inventioncomprises the components (A), (B), (C) and (D). A variety of proceduresare applicable to the preparation of the catalyst, including (1) amethod in which the component (D) is added to the reaction product amongthe components (A), (B) and (C) to prepare the polymerization catalyst,which is brought into contact with monomer/s to be polymerized; (2) amethod in which the components (B) and (C) are added to the reactionproduct between the components (A) and (D) to prepare the catalyst,which is brought into contact with monomer/s to be polymerized; and (3)a method in which the components (A), (B), (C) and (D) are added one byone to monomer/s to be polymerized to bring each of the components intocontact with the monomer/s. There may be employed the reaction productamong the components (A), (B) and (C) which has been isolated andpurified in advance.

The addition and contact of each of the components (A), (B), (C) and (D)may be carried out, of course, at the polymerization temperature andbesides at a temperature in the range of 0 to 100° C.

In producing the styrenic polymer according to the process of thepresent invention, at least one styrenic monomer such as styrene and/ora derivative thereof exemplified by alkylstyrene, alkoxy styrene,halogenated styrene, vinyl benzoate ester or the like is polymerized orcopolymerized in the presence of the combined catalyst comprising theabove-mentioned components (A), (B), (C) and (D). As describedhereinbefore, there are available various methods of bringing thecatalyst of the present invention into contact with the styrenicmonomer.

The polymerization of the styrenic monomer may be carried out in bulk orin a solvent such as an aliphatic hydrocarbon exemplified by pentane,hexane and heptane; an alicyclic hydrocarbon exemplified by cyclohexane;or an aromatic hydrocarbon exemplified by benzene, toluene and xylene.The polymerization temperature is not specifically limited, but isusually 0 to 90° C., preferably 20 to 70° C.

For the purpose of modifying the molecular weight of the styrenicpolymer to be produced, it is effective to proceed with thepolymerization reaction in the presence of hydrogen.

The styrenic polymer obtained by the process according to the presentinvention has a high degree of syndiotactic configuration.

Here, the styrenic polymer which has a high degree of the syndiotacticconfiguration means that its stereochemical structure is mainly thesyndiotactic configuration, i.e. the stereostructure in which phenylgroups or substituted phenyl groups as side chains are locatedalternately at opposite directions relative to the main chain consistingof carbon-carbon bonds. Tacticity is quantitatively determined by thenuclear magnetic resonance method (¹³ C-NMR method) using carbonisotope. The tacticity as determined by the ¹³ C-NMR method can beindicated in terms of proportions of structural units continuouslyconnected to each other, i.e., a diad in which two structural units areconnected to each other, a triad in which three structural units areconnected to each other and a pentad in which five structural units areconnected to each other. "The styrenic polymers having such a highdegree of syndiotactic configuration" as mentioned in the presentinvention means polystyrene, poly(alkylstyrene), poly(halogenatedstyrene), poly(alkoxystyrene), poly(vinyl benzoate), the mixturesthereof, and copolymers containing the above polymers as maincomponents, having such a syndiotacticity that the proportion of racemicdiad is at least 75%, preferably at least 85%, or the proportion ofracemic pentad is at least 30%, preferably at least 50%.Poly(alkylstyrene) include poly(methylstyrene), poly(ethylstyrene),poly(isopropylstyrene), poly(tertbutylstyrene) etc., poly(halogenatedstyrene) include poly(chlorostyrene), poly(bromostyrene),poly(fluorostyrene), etc, and poly(alkoxystyrene) includepoly(methoxystyrene, poly(ethoxystyrene), etc.

The most desirable styrene polymers among them are polystyrene,poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene),poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), andthe copolymer of styrene and p-methylstyrene.

In summary, the process according to the present invention exhibitsremarkable effect in that the range of the molecular weight distributionof the product styrenic polymer is expanded, since the incorporation ofthe organoaluminum compound causes the polymer portion produced by thealuminoxane to shift to the side of lower molecular weight withoutcausing the polymer portion produced by the ion complex to shift to saidside; the molecular weight distribution thereof can be regulated to adesired value by the use of a plurality of transition metal compounds;and the resultant polymer is minimized in residual metallic componentseven when deashing treatment is omitted. After all, highly syndiotacticstyrenic polymer with a wide and arbitrary range of molecular weightdistribution can be efficiently produced at a low production cost by theprocess according to the present invention.

In the following, the present invention will be described in more detailwith reference to non-limitative examples.

EXAMPLE 1

In a 20 mL vessel which had been dried and purged with nitrogen weresuccessively placed 10 mL of styrene and 15 μ mol oftriisobutylaluminum, 10 μmol of methylaluminoxane, 0.50 μmol ofdimethylanilinium tetra(pentafluorophenyl)borate(DMAB) and, 0.50 μmol ofpentamethylcyclopentadienyltrimethyltitanium to proceed withpolymerization at 70° C. for 4 hours. After the completion of thereaction, the reaction product was dried to afford 3.79 g of a polymer.The resultant polymer was cut into slices of 1 mm or less in thickness,which were subjected to Soxhlet extraction for 6 hours by the use ofmethyl ethyl ketone (MEK) as the solvent to produce MIP (MEK-insolubleportion). As the result, syndiotactic polystyrene (SPS) was obtained ata yield of 3.60 g. As the result of analysis by gel permeationchromatography, the SPS had a weight-average molecular weight(Mw)/number-average molecular weight (Mn) ratio (Mw/Mn) of 5.2.

EXAMPLE 2

In a 20 mL vessel which had been dried and purged with nitrogen weresuccessively placed 10 mL of styrene and 15 μ mol oftriisobutylaluminum, 100 μmol of methylaluminoxane, 0.50 μmol ofdimethylanilinium tetra(pentafluorophenyl)borate(DMAB) and, 0.25 μmol of1,2,3,4-tetramethylcyclopentadienyltrimethyltitanium to proceed withpolymerization at 70° C. for 4 hours. After the completion of thereaction, the reaction product was dried to afford 3.11 g of a polymer.The resultant polymer was cut into slices of 1 mm or less in thickness,which were subjected to Soxhlet extraction for 6 hours by the use ofmethyl ethyl ketone (MEK) as the solvent to produce MIP (MEK-insolubleportion). As the result, syndiotactic polystyrene (SPS) was obtained ata yield of 3.16 g. As the result of analysis by gel permeationchromatography, the SPS had a weight-average molecular weight(Mw)/number-average molecular weight (Mn) ratio (Mw/Mn) of 8.3.

EXAMPLE 3

In a 20 mL vessel which had been dried and purged with nitrogen wereplaced 10 mL of styrene and 15 μmol of triisobutylaluminum, 100 μmol ofmethylaluminoxane, and 0.50 μmol of ferroceniumtetra(pentafluorophenyl)borate (FCB) and, after one (1) minute, werefurther added 0.25 μmol of pentamethylcyclopentadienyltitaniumtrimethoxide and 0.25 μmol of1,2,3,4-tetramethylcyclopentadienyltitanium trimethoxide to proceed withpolymerization at 70° C. for 4 hours. After the completion of thereaction, the reaction product was dried to afford 4.80 g of a polymer.The resultant polymer was cut into slices of 1 mm or less in thickness,which were subjected to Soxhlet extraction for 6 hours by the use ofmethyl ethyl ketone (MEK) as the solvent to produce MIP (MEK-insolubleportion). As the result, syndiotactic polystyrene (SPS) was obtained ata yield of 4.68 g. As the result of analysis by gel permeationchromatography, the SPS had a weight-average molecular weight(Mw)/number-average molecular weight (Mn) ratio (Mw/Mn) of 13.2.

What is claimed is:
 1. A process for producing a styrenic polymer whichcomprises polymerizing at least one styrenic monomer by the use of apolymerization catalyst comprising in combination (A) a plurality oftransition metal compounds, (B) an aluminoxane, (C) a coordinationcomplex compound comprising a cation and an anion in which a pluralityof radicals are bonded to a metal and (D) an organoaluminum compound,and wherein at least one of said transition metal compounds (A) is:

    TiRXYZ                                                     (III)

wherein R represents a cyclopentadienyl group, a substitutedcyclopentadienyl group or an indenyl group; X, Y, and Z, independentlyof one another, are a hydrogen atom, an alkyl group having 1 to 12carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbonatoms, an arylalkyl group having 6 to 20 carbon atoms or a halogen atom;or: ##STR4## wherein R⁵ and R⁶ each represent a halogen atom, an alkoxygroup having 1 to 20 carbon atoms or an acyloxy group; and k is aninteger from 2 to 20; and wherein component (A) is present in an amountbetween 0.25 μmol and 0.5 μmol and component (B) is present in an amountof between 10 μmol and 100 μmol per 10 mL of styrenic monomer.
 2. Theprocess according to claim 1 where the aluminoxane is analkylaluminoxane.
 3. A catalyst for polymerizing a styrenic monomer intoa syndiotactic polystyrene which comprises in combination (A) aplurality of transition metal compounds, (B) an aluminoxane, (C) acoordination complex compound comprising a cation and an anion in whicha plurality of radicals are bonded to a metal and (D) an organoaluminumcompound, and wherein at least one of said transition metal compounds(A) is:

    TiRXYZ                                                     (III)

wherein R represents a cyclopentadienyl group, a substitutedcyclopentadienyl group or an indenyl group; X, Y, and Z, independentlyof one another, are a hydrogen atom, an alkyl group having 1 to 12carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbonatoms, an arylalkyl group having 6 to 20 carbon atoms or a halogen atom;or: ##STR5## wherein R⁵ and R⁶ each represent a halogen atom, an alkoxygroup having 1 to 20 carbon atoms or an acyloxy group; and k is aninteger from 2 to 20; and wherein component (A) is present in an amountbetween 0.25 μmol and 0.5 μmol and component (B) is present in an amountof between 10 μmol and 100 μmol per 10 mL of styrenic monomer to bepolymerized.
 4. The process as claimed in claim 2, wherein at least oneof said transition metal compounds (A) is a compound of formula III. 5.The catalyst as claimed in claim 3, wherein at least one of saidtransition metal compounds (A) is a compound of formula III.